[5] Haberlandt has briefly described (‘Die Schutzeinrichtungen...Keimpflanze,’ 1877, p. 77) this curious structure and the purpose which it subserves. He states that good figures of the cotyledon of the onion have been given by Tittmann and by Sachs in his ‘Experimental Physiologie,’ p. 93. A filament, 1.7 inch in length, was affixed nearly upright beneath the knee to the basal and vertical portion of a cotyledon; and its movements were traced during 14 h. in the usual manner. The tracing here given (Fig. 47) indicates circumnutation. The movement of the upper part above the knee of the same cotyledon, which projected at about an angle of 45° above the horizon, was observed at the same time. A filament was not affixed to it, but a mark was placed beneath the apex, which was almost white from beginning to wither, and its movements were thus traced. The figure described resembled pretty closely that above given; and this shows that the chief seat of movement is in the lower or basal part of the cotyledon. Fig. 47. Allium cepa: circumnutation of basal half of arched cotyledon, traced in darkness on horizontal glass, from 8.15 A.M. to 10 P.M. Oct. 31st. Movement of bead magnified about 17 times. Asparagus officinalis (Asparageae).—The tip of a straight plumule or cotyledon (for we do not know which it should be called) was found at a depth of .1 inch beneath the surface, and the earth was then removed all round to the dept of .3 inch. a glass filament was affixed obliquely to it, and the movement of the bead, magnified 17 times, was traced in darkness. During the first 1 h. 15 m. the plumule moved to the right, and during the next two hours it returned in a roughly parallel but strongly zigzag course. From some unknown cause it had grown up through the soil in an inclined direction, and now through apogeotropism it moved during nearly 24 h. in the same general direction, but in a slightly zigzag manner, until it became upright. On the following morning it changed its course completely. There can therefore hardly be a doubt that the plumule circumnutates, whilst buried beneath the ground, as much as the pressure of the surrounding earth will permit. The surface of the soil in the pot was now covered with a thin layer of very fine argillaceous sand, which was kept damp; and after the tapering seedlings had grown a few tenths of an inch in height, each was found surrounded by a little open space or circular crack; and this could be accounted for only by their having circumnutated and thus pushed away the sand on all sides; for there was no vestige of a crack in any other part.